In recent years, there have been developed head mount type image display apparatuses, namely HMDs (Head Mount Display), for the purposes of appreciation of content images such as movies and video, and remote operation of industrial devices or medical devices, and the like.
A HMD is mounted on the head or face of an observer attachably and detachably, and directly projects an image onto an eye of the observer by an eyepiece optical system, the image obtained from an image display device such as a liquid crystal display device and inorganic EL, thereby achieving observation of a virtual image as if the obtained image ware enlarged and projected in the air.
A HMD in such a structure supply a wearer with images, and usually includes a speaker (ear phone) to supply sound also.
Herein, realistic sensation of sound is important so that a wearer is immersed in the world of images. However the shape and size, and the relative position relationship between the head and ears are different depending on each wearer. Accordingly, it is necessary that the position of a speaker is adjustable to an optical position so that the wearer can appreciate realistic sound without sound leakage. In this situation, various mechanisms have been studied so that the position of a speaker can be adjusted, depending on the position of an ear of a wearer.
For example, a technology for a glasses type image display apparatus (refer to Patent Document 1: Japanese Patent Application Publication TOKKAI No. H5-183838) is disclosed that integrates ear hook sections and the respective earphones, and position-adjustably fits them on a cover in a glasses form so as to adjust the positions of the ear hook sections and the positions of earphones simultaneously. Disclosed is a technology (refer to Patent Document 2: Japanese Patent Application Publication TOKKAI No. H9-130705) of a head mount type image display apparatus that supports the main body of an image display apparatus on the head of an observer, and moves support members provided with speakers corresponding to the shape of the head, thereby adjusting the positions of the speakers. Further, disclosed is a technology (refer to Patent Document 3: Japanese Patent Application Publication TOKKAI No. H11-271667) of a visual apparatus provided with earphones that are connected with the main body of the apparatus via cables and can be housed in the main body of the apparatus, wherein the earphones are pulled out from the main body and are directly inserted in the ears of a wearer for appreciation of sound.
However, the technology disclosed in Patent Document 1 does not allow pulling out the earphones from the main body of the apparatus to directly insert them into ears. Consequently, it is not possible to clearly hear sound in a noisy environment. Further, it causes problems of losing secrecy due to sound leakage and irritating others with discomfort. Further, it is understood that it is difficult to surely locate earphones at the positions of ears, the positions of ears being different depending on wearers. Still further, since the earphones cannot be attached to nor detached from the main body of the apparatus, it is understood that it is difficult to make the apparatus in a compact size so as to be put away. In the technology disclosed by patent Document 2, since moving the speakers changes the head holding shape, it is understood that it is difficult to surely locate the earphones at the positions of ears, wherein the positions of ears are different depending on wearers. Further, this may cause sound leakage, and accordingly secrecy may be lost. According to the technology disclosed by Patent Document 3, since the apparatus is not provided with a position adjustment mechanism for earphones, it is always necessary to pull out the earphones from the main body of the apparatus and insert them into ears in order to appreciate sound, and is it also necessary to simultaneously take off the earphones from the ears in order to take off the apparatus from the head. Thus, the operability greatly decreases.
In this situation, an object of the present invention is to provide an image display apparatus, which is mounted on a head or face attachably and detachably and allows viewing of images and hearing sound, that is always supported on the head in a stable state without being affected by the variation of the shape of the head and the position of the ear of a wearer, inhibits leakage of sound, and supplies extremely realistic sound, eliminating the complication and high price of the apparatus.